I recently put in 1 gallon of diesel fuel in my car when it was almost empty and then later had an accident and car . slid in ditch but no impact. Yesterday it started after putting alittle gas in but today it doesnt start. Could it be because car was on an incline for to long and it could be battery or oil went over top of things because it did smoke when it was cranked

Let me understand; put diesel fuel in a car designed for gasoline? If so your looking at a whirl of other issues. Diesel fuel is not as combustable as gasoline and requires much more compression (almost double) then a gasoline vehicle, also diesel fuel is more oily and will gel up in cold temps which is why there is a heater on the motor to warm the fuel before entering the combustion chamber and third the engine needs to be pre warmed (glow plugs) to help ignite the diesel fuel. I would start by flushing the engines fuel system/tank and hopefully the injectors/fuel pump werent damaged/clogged. Its prob smoking because the fuel isnt igniting 100% and its like burning oil, it doesn't combust/explode like gasoline it just burns black due to incomplete combustion.